If you are playing a Buffet Tradition clarinet, I expect it is fairly new since that instrument has only been available for a couple of years. Perhaps this instrument would benefit from some key regulation, or perhaps some finger exercises crossing the break is all that is needed.

If your reeds are a bit too heavy, finger connection and fluency crossing the break can be affected. I always suggest playing reeds which are as light as possible while providing a supported sound which is in tune in all registers and dynamics, and provides secure response under all applications.

This isn't an easy task, so finding a set of litmus tests can be helpful.

Brahms 3 (mvt. 1) solo. Can you play this in one breath? If not then your setup maybe too hard. It isn't an easy ask, but it is something to strive for. Also I want this solo to have even and matched resonances (note the first three notes G, A, B). A good reed should help here.

Brahms 3 (mvt. 2) for fluid and even tonal depth crossing the break, access to warm nuanced and subtle dynamic variation with pure and even sound throughout.

Mendelssohn scherzo. This is a highly reed contingent solo which requires control, impeccable response, and stability for a good and reliable experience. (Crossing the break here quite a bit, so this is also a good check for your reed).

And on to the instrument's proper regulation. The comments above were great.

A good bell can help center your sound when crossing the break, it can help subtle intonation issues, and it can help lighten your instrument as well. But the bell which came with your Tradition instrument is indeed a good start, and I wouldn't recommend getting a new bell until you have sorted the above options first. Furthermore, bells are very influential in the playing experience, but not required like a good mouthpiece, reed, and barrel (length) in order to function in ensemble. So make sure your level is sufficient to warrant such an addition. Yes there are many options when it comes to bells, and this is where attendance at an ICA conference can be wonderful. It gives the opportunity to try everything before you buy.

When aftermarket bells became the rage back around the year 2000, I resisted. I tried a few and found them to be different but not necessarily better. It took me about 15 years to finally find something which was better than my stock Buffet bell, and I actually had to make it for my concept of the optimum playing experience. It wasn't something I planned to make for the marketplace, but rather as an experiment. I always felt that by reducing the ID of my equipment's bore dimensions, improvements became evident. By reducing the barrel's bore size, by selecting golden-era Buffet R13 clarinets which happened to have small bores, and eventually by making bells with smaller bore dimensions, my sound focused better, and my comfort increased as well. I call it "autofocus." So I decided to go for it.